1. Field of the Invention
The present invention relates to a signal processing apparatus and a method, a record medium and a program. More particularly, the invention relates to a signal processing apparatus and a method, a record medium and a program with which it is capable of eliminating properly a ringing component from a contour correction signal.
2. Description of Related Art
FIG. 1 shows the configuration of a signal processing apparatus 1 that processes a video signal from a conventional CCD (charge coupled device) camera, which is discussed in, for example, “Introduction to CCD Camera Technique” by Hiroo Takemura, Corona Publishing Co., Ltd., pp. 144-145.
A VLPF (vertical low pass filter) 11 performs vertical low pass filtering processing of a video signal (hereinafter referred to as an input video signal) from a CCD camera (not shown), and outputs a resultant signal to a luminance signal generating section 12 and a contour correction signal generating section 13.
The luminance signal generating section 12 includes, for example, a horizontal LPF and the like, and generates from the signal inputted from the VLPF 11 a horizontal luminance signal having frequency characteristics as indicated by a dotted line A in FIG. 2.
The contour correction signal generating section 13 generates from the signal inputted from the VLPF 11 a horizontal contour correction signal (a high frequency region signal) having frequency characteristics as indicated by a solid line B in FIG. 2, and then outputs this correction signal to an adder 14.
FIG. 3 shows an example of the configuration of the contour correction signal generating section 13.
The signal from the VLPF 11 is inputted to a delay circuit 21 and an adding circuit 23. The delay circuit 21 delays the inputted signal for an arbitrary time τ, and then outputs a resultant signal to a delay circuit 22 and a subtracting circuit 25.
The delay circuit 22 further delays the signal inputted from the delay circuit 21 for the time τ and then outputs a resultant signal to the adding circuit 23.
The adding circuit 23 adds the signal from the VLPF 11 and the signal from the delay circuit 22, and then outputs a resultant signal to a dividing circuit 24.
The dividing circuit 24 divides the signal inputted from the adding circuit 23 into halves, and then outputs a resultant signal to the subtracting circuit 25. The subtracting circuit 25 subtracts the signal inputted from the dividing circuit 24 from the signal inputted from the delay circuit 21, and then outputs a resultant signal to the adder 14 (FIG. 1), as a horizontal contour correction signal.
In the adder 14, a luminance signal from the luminance signal generating section 12 and a horizontal contour correction signal from the contour correction signal generating section 13 are added, and a resultant signal (luminance signal) is then outputted to the luminance signal processing circuit 15.
By adding the horizontal contour correction signal of high frequency region to the luminance signal as described above, the luminance signal once falls temporarily at the time of rise, and then rises, and returns after exceeding a predetermined level, so that it is able to improve sharpness of the entire image.
The luminance signal processing circuit 15 performs processing, such as adding a synchronizing signal and a blanking signal to the luminance signal inputted from the adder 14.
However, the horizontal contour correction signal generated by the conventional contour correction generating section 13 (FIG. 3) contains image quality degrading components without change (ringing components and the like), as indicated by dotted circles R in FIG. 4. The conventional manner of correcting a luminance signal by a contour correction signal suffers from the problem that ringing occurs in an edge peripheral portion, or aliasing occurs, thus degrading image quality.
Therefore, there is a need for eliminating such image quality degrading components from a contour correction signal of high frequency region thereby to suppress image quality degradation due to ringing and the like.